Buy Phaeton with “door rust”?

Hello forum, I have been looking for a V8 for some time now. Due to the set purchase limit of about 10 t€ almost only vehicles with an age around the 10 years come into consideration. These are mostly with private people or with flags dealers – so nothing with VW carefree guarantee. Many of the vehicles I looked at have more or less pronounced “alurost bubbles” on the door edges ( trims ok). If you know that they exist, you can find them almost always… I have already a h ier read through the forum – but mostly it was about younger vehicles, which VW often repaired on Kulanz. So now my questions: How do these rust bubbles develop? Are they still bursting up and getting really ugly? With a 10 year old Phaeton I certainly no longer need to hope for Kulanz from VW, do I? Greet Benjamin